We’ve had many good laughs here on Dogster talking about dogs and marijuana. The funny stories and innuendos have all been based on one important fact: Although dogs can get stoned and have bad trips, marijuana toxicity doesn’t kill dogs. I’m sorry to say it, but the good times may be coming to an end. Marijuana, especially the medical grade stuff, has gotten so potent that it is now killing dogs.

I recently came across an interesting paper in the Journal of the Veterinary Emergency and Critical Care Society titled “Evaluation of trends in marijuana toxicosis in dogs living in a state with legalized medical marijuana: 125 dogs (2005-2010).”

The papaer discusses a study done in Colorado after marijuana was legalized for medical purposes, but before the vote on general legalization occurred last November. The study aimed to determine whether legalizing marijuana for medical use correlated to an increase in canine marijuana toxicity.

And indeed it did. During the study period, medical marijuana registrations increased 146-fold. During the same time, cases of canine marijuana toxicity increased fourfold. To quote the authors, “A significant positive correlation was detected between the increase in known/suspected marijuana toxicosis in dogs … and the increased number of medical marijuana licenses.”

This is hardly surprising. If there’s more marijuana around, there will be more opportunities for exposure. Also, medical marijuana users seem to consume more edible pot products. Dogs like to eat those things, too.

However, what really floored me was this: Two of the dogs in the study died. I had never heard of such a thing before.

THC, the main active ingredient in marijuana, supposedly affects the cerebral cortex but not the brainstem. The brainstem controls vital body functions such as breathing, heart rate, and blood pressure. The theory had been that because the brainstem contains no receptors for THC, it is impossible to die from a THC overdose.

Perhaps dogs have different brainstem receptors. They certainly metabolize THC differently than humans. Either of these features could explain the deaths. Whatever the cause, there are now two dogs on record who have died after consuming marijuana-laced products.

Both dogs in question were relatively small, and both had consumed medical grade marijuana butter. This means that they consumed massive quantities relative to their sizes. It should be noted that chocolate was also present in the concoctions consumed by the two unfortunate canines. However, it appears to be the marijuana that killed them.

My question for medical marijuana producers and consumers is this: How freaking high do you need to get? Must your products be so strong that they launch you into outer space and pose the risk of death to dogs? Whatever happened to pot experiences that included staying on Earth, eating Girl Scout cookies, and listening to Dark Side of the Moon?

The canine threats from marijuana don’t end with medical-grade products. Use of synthetic marijuana also appears to be spreading. This stuff, most commonly called spice, may be even more dangerous to dogs than potent medical-grade marijuana.

I guess times change, and there’s no use pining for the past. I will miss the days when writing about marijuana in dogs was mostly fun and laughs, and I dread the fact that now I must start treating marijuana-intoxicated dogs as if their lives are at risk.

The paper’s bounty of information did not end with the reports of canine marijuana deaths. It also discussed something that should be of interest to vets: Drug testing dogs. Drug tests made for humans can be used on dog urine. They are generally very reliable, with one exception — marijuana. The authors of the papter surmise that this is because dogs metabolize THC differently than humans. The canine metabolite has less affinity for the test, and it is less likely to result in a full positive result. The authors suggest that dogs with symptoms of marijuana intoxication and ambiguous test results might benefit from being treated as if the test result were positive.

Previously, that would have been welcome news. Marijuana used to be uniformly nonlethal, whereas other toxins that caused similar symptoms could be a big deal. However, if current trends continue, a diagnosis of marijuana toxicity in a dog might be a serious one after all.

The paper discussed in this article is Meola, et al J Vet Emerg Crit Care 2012; 22(6): 690-696.

More articles on digestive issues and poisons:

• Why Is Chocolate Toxic to Dogs?
• My Dog Is Vomiting. When Is It Time to Go to the Vet?
• Poisonous Plants and Foods for Dogs

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